The present invention relates generally to quick disconnects and more particularly to quick disconnects for use between a power supply and a torch lead in a plasma arc torch through which both fluid (e.g. gas, liquid) and electrical power are conducted.
In manually operated plasma arc torches of the known art, a torch is commonly connected to a power supply through a torch lead, which is typically available in a variety of lengths according to requirements of a specific application. Additionally, the torch lead is often secured to the power supply using a quick disconnect such that the torch lead may be quickly and easily removed from the power supply in the event that the torch and/or torch lead is damaged or requires replacement. Further, the quick disconnect allows a torch and torch lead to be easily interchanged with a variety of power supplies if necessary.
Typically, the torch lead side of the quick disconnect comprises a housing, commonly in the form of a plug, with a variety of electrical and fluid, (e.g., gas, liquid), conductors disposed therein. Similarly, the power supply side of the quick disconnect also comprises a housing, commonly in the form of a socket, adapted to receive the plug, with a mating set of electrical and gas conductors disposed therein. Generally, the mating conductors comprise one or more main power pins and mating sockets that conduct both electric power and fluid for operation of the torch, wherein high current, high voltage, and/or high frequency electrical power is provided to initiate and operate a plasma arc. Further, a plurality of signal pins and mating signal sockets conduct electrical signals for operation of the torch such as a trigger switch or electrical grounding, among others. Moreover, some or all of the mating conductors, including the main power pins and sockets, may be replaceable such that an inoperative or broken conductor may be replaced in the field as necessary.
The majority of quick disconnects that connect a plasma arc torch lead to a power supply comprise a threaded connection between the torch lead side of the connection and the power supply side of the connection. Typically, a locking ring is disposed around one housing or the other, and after the individual conductors and the housings are engaged, internal threads of the locking ring engage external threads of one of the housings, typically the socket housing, to secure the connection therebetween. Unfortunately, the quick disconnects of the known art comprise a relatively fine pitch thread that requires several turns of the locking ring in order to fully engage the quick disconnect. Additionally, no indication of a fully mated condition of the quick disconnect is provided in connectors of the known art. Rather, a user tightens the locking ring until the locking ring cannot be turned any further. Moreover, it is often difficult to properly engage the threads to initiate a connection since the threads must generally be aligned, in addition to aligning the conductors within the housings, which often causes a significant amount of rotation of the locking ring to initiate threaded contact. Engagement is particularly difficult and time consuming when the threads of the locking ring and the housing comprise a finer pitch. To simplify threaded contact, known art connectors have employed coarser threads in order to facilitate ease of connection. However, a finer pitch generally results in a more robust and reliable connection and thus the coarser threads reduce the robustness and reliability of the connection. Accordingly, a trade-off exists between ease of connection and a robust and reliable connection in threaded connectors of the known art.
Therefore, quick disconnects for plasma arc torches of the known art are typically heavy and bulky in order to accommodate the multitude of electrical and gas conductors disposed therein. As a result, connecting and disconnecting a torch lead to and from a power supply is often cumbersome and difficult in the field. Further, proper alignment of the individual fluid and electrical conductors disposed within each side of the quick disconnect becomes more difficult with the heavy and bulky quick disconnects. Moreover, the use of a threaded connection between the housings, especially when the threads comprise a finer pitch, results in an even more difficult quick disconnect to engage and disengage.
Additionally, the conductors of known art quick disconnects are often prone to damage when the quick disconnect is disengaged since the conductors often extend or protrude beyond the ends of their respective housings. Further, when a conductor is damaged or broken in the field, an improper conductor may inadvertently be used to replace the damaged conductor such that unsuitable equipment, e.g. torches, are mistakenly connected to the power supply. As a result, the torch may function improperly or parts may wear prematurely. In addition, the torch can be damaged or operate improperly when disengaging quick disconnects of the known art as all of the connections are typically broken simultaneously, or in some instances, the gas continues to flow even when the quick disconnect is not fully engaged. Consequently, the plasma arc torch may become damaged or difficult to operate should an inadvertent disengagement of the quick disconnect occur during operation of the torch.
Accordingly, a need remains in the art for a quick disconnect for use between a power supply and a plasma arc torch that is relatively compact and easy to engage, and which further provides a positive indication of a fully mated condition. A further need exists for a quick disconnect that reduces the risk of damage to the conductors disposed therein and that reduces the risk of replacing a damaged conductor with an improper conductor, thereby improving the performance of a plasma arc torch. Moreover, a need exists for a quick disconnect that reduces the risk of arcing and that prevents damage to the plasma arc apparatus when a quick disconnect is not fully engaged.
In one preferred form, the present invention provides a quick disconnect for use between a power supply and a torch lead in a plasma arc apparatus such as a plasma arc cutting torch, hereinafter referred to as a plasma arc torch. Generally, the quick disconnect provides a connection for both fluid, (e.g., gas, liquid), flow and electrical power between the power supply and the torch, while providing a connection that may be quickly engaged and disengaged in the field. Further, as used herein, a plasma arc apparatus, whether manual or automated, shall be construed by those skilled in the art to be an apparatus that generates or uses plasma for cutting, welding, spraying, or marking operations, among others. Accordingly, the specific reference to plasma arc cutting torches or plasma arc torches herein should not be construed as limiting the scope of the present invention.
According to one form of the present invention, the quick disconnect comprises a plug housing secured to a torch lead that engages a socket housing secured to a power supply, wherein a locking ring disposed around the plug housing engages the socket housing to secure the plug housing to the socket housing. Alternately, the plug housing may be secured to the power supply, and the socket housing may be secured to the torch lead. Further, a plurality of both fluid and electric conductors are disposed within the plug and socket housings, which include but are not limited to, a negative lead gas carrying pin secured within the plug housing, or alternately the socket housing, that engages a main power socket secured within the socket housing, or alternately the plug housing. In addition, a plurality of signal pins are disposed within the plug housing, or alternately the socket housing, that engage a plurality of signal sockets disposed within the socket housing, or alternately the plug housing. Moreover, a pilot return pin is disposed within the plug housing, or alternately the socket housing, that engages a pilot return socket disposed within the socket housing, or alternately the plug housing. Additionally, the negative lead gas carrying pin and the main power socket are positioned off-center in order to provide additional volume for the signal pins and the pilot return pin, thereby resulting in a relatively compact quick disconnect.
Preferably, the plug and socket housings further define a D-configuration to align the housings and their respective conductors for proper engagement. Further, the quick disconnect comprises a signal pin shroud at a distal end of at least one of the plug or socket housing that separates the conductors to provide a dielectric barrier therebetween. Moreover, the main power socket preferably comprises a plurality of fingers to engage the negative lead gas carrying pin, which are separated by axial slots having a certain length. Additionally, the main power socket defines an undercut at a proximal end thereof, wherein a plurality of radial contact pads engage the negative lead gas carrying pin. Accordingly, the required length of the axial slots is reduced with the undercut and the radial contact pads, thereby resulting in a shorter main power socket and a more compact quick disconnect. Furthermore, more than one negative lead gas carrying pin, or main pin that conducts either or both electrical power and fluid, may be disposed within the plug housing, with a corresponding plurality of main power sockets disposed within the socket housing for operation of a plasma arc torch with more than one fluid, (e.g. gas, liquid), supply.
In another preferred form, a connector is provided that comprises a socket housing defining a D-configuration and a plug housing having a corresponding D-configuration, which shape forces a particular orientation of the plug housing within the socket housing. Further, a locking ring disposed around the plug housing engages the socket housing to secure the plug housing to the socket housing. Additionally, a plurality of fluid and electrical conductors are disposed within the housings such that the connector provides a connection for both fluid and electric power in a single connector.
In yet another preferred form, a plug housing is provided for use in a quick disconnect for a plasma arc torch that comprises a hollow internal channel positioned off-center the plug housing in order to provide additional volume for further conductors disposed therein. Further, the plug housing defines a D-configuration to align the plug housing with a mating socket housing. Moreover, the plug housing comprises a plurality of signal pin channels and a pilot return channel for disposition of additional electrical conductors for operation of the plasma arc torch.
In another preferred form, a socket housing is provided for use in a quick disconnect for a plasma arc torch that comprises a main power socket aperture positioned off-center the socket housing in order to provide additional volume for further conductors disposed therein. Additionally, the socket housing defines a D-configuration to align the socket housing with a mating plug housing. Moreover, the socket housing comprises a plurality of signal pin apertures and a pilot return aperture for disposition of additional electrical conductors for operation of the plasma arc torch.
In yet another preferred form, a connector is provided that generally comprises a housing defining a first threaded portion and a second threaded portion, wherein the first threaded portion comprises a pitch that is coarser than a pitch of the second threaded portion. A locking ring is also provided that defines a thread engagement member that engages the first threaded portion and the second threaded portion to secure the locking ring to the housing with a varying amount of axial travel per rotation of the locking ring that corresponds with the pitch of the first threaded portion and the second threaded portion. Accordingly, the connector is relatively simple to engage as the thread engagement member engages the coarser threads of the first threaded portion. Furthermore, a robust and reliable connection is provided as the thread engagement member engages the finer threads of the second threaded portion as the locking ring is further rotated.
Additionally, the thread engagement member preferably comprises two diametrically opposed radial protrusions that engage the first threaded portion and the second threaded portion as the locking ring is rotated. Further, the housing preferably comprises thread protrusions disposed within the second threaded portion such that the radial protrusions on the locking ring engage the thread protrusions on the housing to provide an audible and/or tactile indication of a fully mated condition between the locking ring and the housing. Additionally, a lateral stop is disposed at an end of the second threaded portion to limit travel of the locking ring.
In another form, a connector is provided that comprises a housing defining a hollow internal channel, wherein a plurality of locking fingers are disposed that engage a pin to secure the pin within the housing. Accordingly, the pin defines a first collar with a shoulder disposed thereon such that the locking fingers engage the shoulder to secure the pin within the housing. Additionally, the hollow internal channel further comprises a first portion and the pin further defines a second collar such that the second collar blocks access to the locking fingers through the first portion. As a result, the locking fingers cannot be accessed to disengage the pin as the second collar engages the first portion of the hollow internal channel. Furthermore, the pin is recessed within a second portion of the hollow internal channel when the locking fingers fully engage the shoulder, thereby restricting access to the pin such that the connection remains tamper resistant.
In yet another form, a pin for use in a quick disconnect of a plasma arc torch is provided that generally comprises an o-ring groove disposed around a cylindrical portion of the pin. Further, an o-ring removal slot is provided in the pin that adjoins the o-ring groove, such that the o-ring removal slot provides access for removal of an o-ring disposed within the o-ring groove. In one form, the o-ring groove is recessed within a housing of the quick disconnect to protect the pin during use. Therefore, the o-ring, which provides a fluid-tight seal between the pin and a mating socket, is difficult to remove for inspection and/or replacement. Accordingly, the o-ring removal slot provides the requisite access to remove the o-ring from the recessed o-ring groove, using, for example, an o-ring removal tool.
In another form, a quick disconnect for use in a plasma arc torch is provided, wherein specific conductors disposed within the quick disconnect are configured to disengage in a specific sequence in order to improve the performance of the plasma arc torch. Generally, upon disengagement of the quick disconnect, signal connections break before a pilot return connection, a fluid connection, and a main power connection. Further, the pilot return connection breaks before the fluid connection and the main power connection, and the fluid connection breaks before the main power connection. Accordingly, a make-break timing sequence is provided through establishing specific connection configurations and specific lengths of connections throughout the quick disconnect.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.